<template>
  <div class="app-container">
    <!--表单-->
    <el-form :inline="true" class="demo-form-inline">
      <el-form-item>
        <el-date-picker
          v-model="startDate"
          type="date"
          placeholder="选择开始日期"
          value-format="yyyy-MM-dd" />
      </el-form-item>
      <el-form-item>
        <el-date-picker
          v-model="endDate"
          type="date"
          placeholder="选择截止日期"
          value-format="yyyy-MM-dd" />
      </el-form-item>
      <el-button
        :disabled="btnDisabled"
        type="primary"
        icon="el-icon-search"
        @click="showChart()">查询</el-button>
    </el-form>
    <div id="chart" class="chart" style="height:500px;" />
  </div>
</template>
<script>
import echarts from 'echarts'
import api from '@/api/vod/videoVisitor'

export default {
  data() {
    return {
      courseId: '',
      startDate: '',
      endDate: '',
      btnDisabled: false
    }
  },
  created() {
    this.courseId = this.$route.params.id
    // 初始化最近十天数据
    let currentDate = new Date();
    this.startDate = this.dateFormat(new Date(currentDate.getTime()-7*24*3600*1000))
    this.endDate = this.dateFormat(currentDate)
    this.showChart()
  },
  methods: {
    showChart() {
      api.findCount(this.courseId, this.startDate, this.endDate).then(response => {
        this.setChartData(response.data)
      })
    },
    setChartData(data) {
      // 基于准备好的dom，初始化echarts实例
      var myChart = echarts.init(document.getElementById('chart'))
      // 指定图表的配置项和数据
      var option = {
        title: {
          text: '观看课程人数统计'
        },
        xAxis: {
          data: data.xData
        },
        yAxis: {
          minInterval: 1
        },
        series: [{
          type: 'line',
          data: data.yData
        }]
      }
      // 使用刚指定的配置项和数据显示图表。
      myChart.setOption(option)
    },
    dateFormat(date) {
      let fmt = 'YYYY-mm-dd'
      let ret;
      const opt = {
        "Y+": date.getFullYear().toString(),        // 年
        "m+": (date.getMonth() + 1).toString(),     // 月
        "d+": date.getDate().toString(),            // 日
        "H+": date.getHours().toString(),           // 时
        "M+": date.getMinutes().toString(),         // 分
        "S+": date.getSeconds().toString()          // 秒
        // 有其他格式化字符需求可以继续添加，必须转化成字符串
      };
      for (let k in opt) {
        ret = new RegExp("(" + k + ")").exec(fmt);
        if (ret) {
          fmt = fmt.replace(ret[1], (ret[1].length == 1) ? (opt[k]) : (opt[k].padStart(ret[1].length, "0")))
        };
      };
      return fmt;
    }
  }
}
</script>